1. Field of the Invention
The present invention relates to a die bonding apparatus and, more particularly, to a die bonding apparatus for selectively performing LOC (lead on chip) die bonding and normal die bonding through regulation of a simple control function when bonding semiconductor chips of a memory device from a wafer to lead frames, thereby to increase efficiency in use of equipment and reduce the cost for equipment.
2. Discussion of Related Art
A semiconductor lead frame is one of the core elements constructing a semiconductor package together with a wafer.
It has been well known that the lead frame serves as both a lead for connecting the inside of the semiconductor package and the outside, or the circuit board, and a frame for supporting a semiconductor chip.
This semiconductor lead frame is made in such a manner of forming a predetermined shape out of thin film material using a press dies sequentially transferred or through an etching step utilizing chemicals.
The semiconductor lead frame manufactured through the ways as illustrated above is put together with the other components including a chip of a memory device through an assembly process and, more specifically, constructs the semiconductor package through die bonding and wire bonding.
On the thin film are formed a plurality of unit lead frames which are arranged in all directions, and adhesive tape for the mounting of the chip is applied to the bottom surface, thus forming unit lead frame members.
Each unit lead frame members where the adhesive tape is applied is arranged on a rail through vacuum adsorption and then the die bonding step is performed.
For the die bonding step, a die is picked up through suction by a nozzle from a silicon wafer where multiple dice are formed, each die being a unit device, and then transferred to a predetermined site to be mounted on. Subsequently, each die is transferred below the arranged lead frame and mounted thereon. The bonding is, in turn, performed using things like a thermo-compression bonding machine.
After this bonding step, the lead frame is transferred to passing through the next wire bonding step. During the wire bonding, each lead is connected to the circuit of the die through a metal wire, such as gold or silver having excellent conductivity.
In other words, adhesive tape 2 for the bonding of a chip is applied to the multiple unit lead frames 1 formed out of the thin film in a taping process as illustrated FIG. 1. The lead frame where the adhesive tape 2 applied is then transferred facing downward and the die 3, such as a chip of a memory device, is mounted on the lead frame from below. At the next wire bonding step, the nodes of the die and the lead frame are bonded through the wire 4 by way of LOC die bonding widely used, as shown in FIG. 2a.
Alternatively, adhesive Ag epoxy is applied to the top surface of a lead frame 5 and a die 7 is directly mounted down on the lead frame from above before bonding the nodes of the die 7 to the lead frame 5 using a wire 8 in normal die bonding, as shown in FIG. 2b, which is often used due to its operation efficiency.
At the early stage of development where the size of the die is large, the LOC die bonding is primarily used because an overall package can be reduced, but when it is not necessary to reduce the size of the overall package due to the small size of the die, the normal bonding is used much more frequently than the LOC die bonding.
However, according to the conventional die bonding apparatus, separate apparatus must be used for each LOC die bonding step and normal die bonding step because operations for each step are different, so additional production facilities must be installed. In addition, there is a drawback that the facilities are left and not used because the apparatus for the LOC die bonding or normal die bonding cannot used for other processes.